GAS REGULATION OF GALAXIES: THE EVOLUTION OF THE COSMIC SPECIFIC STAR FORMATION RATE, THE METALLICITY–MASS–STAR-FORMATION RATE RELATION, AND THE STELLAR CONTENT OF HALOS

By S. Lilly, C. Carollo, A. Pipino, A. Renzini, Yingjie Peng. 2013

502 citations recorded by the source corpus.

A very simple physical model of galaxies is one in which the formation of stars is instantaneously regulated by the mass of gas in a reservoir with mass loss scaling with the star-formation rate (SFR). This model links together three different aspects of the evolving galaxy population: (1) the cosmic time evolution of the specific star-formation rate (sSFR) relative to the growth of halos, (2) the gas-phase metallicities across the galaxy population and over cosmic time, and (3) the ratio of the stellar to dark matter mass of halos. The gas regulator is defined by the gas consumption timescale (ε−1) and the mass loading λ of the wind outflow λ·SFR. The simplest regulator, in which ε and λ are constant, sets the sSFR equal to exactly the specific accretion rate of the galaxy; more realistic situations lead to an sSFR that is perturbed from this precise relation. Because the gas consumption timescale is shorter than the timescale on which the system evolves, the metallicity Z is set primarily by the instantaneous operation of the regulator system rather than by the past history of the system. The metallicity of the gas reservoir depends on ε, λ, and sSFR, and the regulator system therefore naturally produces a Z(mstar, SFR) relation if ε and λ depend on the stellar mass mstar. Furthermore, this relation will be the same at all epochs unless the parameters ε and λ themselves change with time. A so-called fundamental metallicity relation is naturally produced by these conditions. The overall mass–metallicity relation Z(mstar) directly provides the fraction fstar(mstar) of incoming baryons that are being transformed into stars. The observed Z(mstar) relation of Sloan Digital Sky Survey (SDSS) galaxies implies a strong dependence of stellar mass on halo mass that reconciles the different faint-end slopes of the stellar and halo mass functions in standard ΛCDM models. The observed relation also boosts the sSFR relative to the specific accretion rate and produces a different dependence on mass, both of which are observed. The derived Z(mstar, SFR) relation for the regulator system is fit to published Z(mstar, SFR) data for the SDSS galaxy population, yielding ε and λ as functions of mstar. The fitted ε is consistent with observed molecular gas-depletion timescales in galaxies (allowing for the extra atomic gas), while the fitted λ is also reasonable. The gas-regulator model also successfully reproduces the Z(mstar) metallicities of star-forming galaxies at z ∼ 2. One consequence of this analysis is that it suggests that the mstar–mhalo relation is established by baryonic processes operating within galaxies, and that a significant fraction (40%) of baryons coming into the halos are being processed through the galaxies. This fraction may be more or less constant. The success of the gas-regulator model in simultaneously explaining many diverse observed relations over the 0 < z < 2 interval suggests that the evolution of galaxies is governed by simple physics that form the basis for this model.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/667dae66df77c549d9f92fa634f45fed34d42b5b

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Citations in the corpus

A HIGHLY CONSISTENT FRAMEWORK FOR THE EVOLUTION OF THE STAR-FORMING “MAIN SEQUENCE” FROM z ∼ 0–6 (2014, background): “THE NON-UNITY SLOPE OF THE MAIN SEQUENCE AND THE STAR-FORMING STELLAR MASS FUNCTION As noted by Peng et al. (2010), Lilly et al. (2013), and Abramson et al. (2014), a MS slope of less than unity implies that the slope αs of the SF mass function below the characteristic mass M∗ should steepen with…”
AN OBJECTIVE DEFINITION FOR THE MAIN SEQUENCE OF STAR-FORMING GALAXIES (2015, unknown): “G A ] 3 F eb 2 01 5 Lilly et al. 2013; Peng & Maiolino 2014).”
COMBINED CO AND DUST SCALING RELATIONS OF DEPLETION TIME AND MOLECULAR GAS FRACTIONS WITH COSMIC TIME, SPECIFIC STAR-FORMATION RATE, AND STELLAR MASS (2014, methodology): “As a result it does somewhat better below 10 10 M but above log(M*/4x10 10 M ) the Lilly et al. (2013) function predicts too high star formation rates and overshoots the observed locus of SFGs.”
xGASS: total cold gas scaling relations and molecular-to-atomic gas ratios of galaxies in the local Universe (2018, background): “1 IN T RO D U C T I O N The gas-star formation cycle is central to the formation and evolution of galaxies (see e.g. Leroy et al. 2008; Lilly et al. 2013 and review by Kennicutt & Evans 2012).”
UniverseMachine: The correlation between galaxy growth and dark matter halo assembly from z = 0−10 (2018, background): “In equilibrium (a.k.a., “steady-state” or “bathtub”) models of galaxy formation (e.g., Bouché et al. 2010; Davé et al. 2010; Lilly et al. 2013), galaxies form stars according to average gas accretion rates scaled by a mass-dependent efficiency.”
THE UNIVERSAL RELATION OF GALACTIC CHEMICAL EVOLUTION: THE ORIGIN OF THE MASS–METALLICITY RELATION (2014, background): “Several authors have recognized variations in the gas content of galaxies as the basis of the observed relation between stellar mass, metallicity and SFR (e.g., Davé et al. 2012; Dayal et al. 2013; Bothwell et al. 2013; Lilly et al. 2013; Davé et al. 2013).”
PHIBSS: Unified Scaling Relations of Gas Depletion Time and Molecular Gas Fractions (2017, methodology): “We find significant evidence for curvature in the μgas-z relation, which tracks the sSFR-evolution, and perhaps indicates deviations from a simple ideal gas regulator with depletion time as its fastest time clock (Lilly et al. 2013).”
The confinement of star-forming galaxies into a main sequence through episodes of gas compaction, depletion and replenishment (2015, methodology): “This is consistent with predictions from a bathtub toy model by Lilly et al. (2013) and Dekel & Mandelker (2014) that predict sSFR ∼ 1/fstar · sAR ∼ 1.5 · sAR at high z, where fstar is the mass fraction retained in long-lived stars after stellar mass loss.”
The origin and evolution of the galaxy mass–metallicity relation (2015, background): “Such models have also been modified to work in cosmological contexts and describe the evolution of MZR (e.g. Finlator & Davé 2008; Davé et al. 2012; Lilly et al. 2013).”
GOODS-HERSCHEL: STAR FORMATION, DUST ATTENUATION, AND THE FIR–RADIO CORRELATION ON THE MAIN SEQUENCE OF STAR-FORMING GALAXIES UP TO z ≃ 4 (2014, background): “Very recently, (Maier et al. 2014) have shown that, when using the formalism put forward in Lilly et al. (2013) or equivalently the equation 2 of Mannucci et al. (2010), as opposed to the equation 5 of the same paper, to describe the FMR, measured highredshift metallicities are overall well…”
BLACK HOLE VARIABILITY AND THE STAR FORMATION–ACTIVE GALACTIC NUCLEUS CONNECTION: DO ALL STAR-FORMING GALAXIES HOST AN ACTIVE GALACTIC NUCLEUS? (2013, methodology): “…evolution in the galaxy stellar mass and luminosity functions (similar to the analysis of Conroy & White 2013) while also accounting for the distribution of SFRs as a function of galaxy mass, as in recent studies of galaxy formation (e.g. Peng et al. 2010; Behroozi et al. 2013; Lilly et al. 2013).”
The mass–metallicity and the fundamental metallicity relation revisited on a fully Te-based abundance scale for galaxies (2019, background): “…relation by means of the interplay between the infall of pristine gas, the so triggered star formation activity and the amount of enriched material expelled through outflows (e.g. Davé et al. 2011; Dayal et al. 2013; Lilly et al. 2013; De Rossi et al. 2015; Davé et al. 2017; Torrey et al. 2018).”
Introducing the Illustris Project: the evolution of galaxy populations across cosmic time (2014, background): “…semi-analytical, and semi-numerical models (Damen et al. 2009; Bouché et al. 2010; Firmani et al. 2010; Davé, Oppenheimer & Finlator 2011; Lilly et al. 2013; Dekel & Mandelker 2014), with possible solutions being rather radical or contrived (Davé 2008; Kang et al. 2010; Weinmann,…”
The Evolution of Galaxy Structure Over Cosmic Time (2014, background): “What is more likely driving the quenching of typical field galaxies is merger driven, or driven by the stellar/halo mass in some form of feedback process (e.g., Peng et al. 2010; Peng et al. 2012; Lilly et al. 2013; Carollo et al. 2013).”
VALIDATION OF THE EQUILIBRIUM MODEL FOR GALAXY EVOLUTION TO z ∼ 3 THROUGH MOLECULAR GAS AND DUST OBSERVATIONS OF LENSED STAR-FORMING GALAXIES (2013, methodology): “(11) The above equation is presentd by Lilly et al. (2013) based on results from a number of recent highredshift imaging surveys (Noeske et al. 2007; Elbaz et al. 2007; Daddi et al. 2007; Pannella et al. 2009; Stark et al. 2012).”
The EAGLE project: Simulating the evolution and assembly of galaxies and their environments (2014, methodology): “…numerical experiments and analytic models provide some support for the general idea (e.g. Finlator & Davé 2008; Schaye et al. 2010; Booth & Schaye 2010; Davé et al. 2012; Haas et al. 2013a,b; Feldmann 2013; Dekel et al. 2013; Altay et al. 2013; Lilly et al. 2013; Sánchez Almeida et al. 2014).”
(Star)bursts of FIRE: observational signatures of bursty star formation in galaxies (2015, background): “M∗ relation plays a central role in galaxy evolution phenomenology, in which the emerging picture is that galaxies build up most of their stellar mass while they are on this relation (e.g. Lilly et al. 2013) and are fuelled by continuous gas supply (Kereš et al. 2005).”
The dark side of galaxy colour (2013, methodology): “…with a minimal set of phenomenological observations based on zCOSMOS data (Lilly et al. 2007) and apply a set of continuity equations to the evolution of the number of red and blue galaxies in order to connect galaxy properties to the dark matter halos hosting them (see also Lilly et al. 2013).”